USGS hydrologist presented at Okefenokee science symposium

The U.S. Geological Survey said SAWSC hydrologist Greg Cherry presented at the Biennial Okefenokee Science Symposium. His presentation focused on the Floridan aquifer system in coastal Georgia and saltwater intrusion in the Savannah/Hilton Head area and near downtown Brunswick, Georgia.

Cherry presented research on groundwater studies and data used to evaluate the effects of water management practices in coastal Georgia. The work covered groundwater development and the role of the USGS in evaluating saltwater intrusion in areas of high pumping in the Upper Floridan aquifer.

According to the announcement, the Georgia Environmental Protection Division established a red zone in 2006 in coastal Georgia. Pumping rates in the Upper Floridan aquifer were capped at 2004 rates because of concern about potential saltwater intrusion in the Savannah-Hilton Head Island area and plume migration toward a potentiometric low in the aquifer.

The red zone includes all of Chatham County and the southern part of Effingham County. Restrictions were implemented to address potential saltwater intrusion and plume migration. In the Brunswick/Glynn County area, saltwater had intruded into the Upper Floridan aquifer and formed a plume with high chloride concentrations near downtown Brunswick.

The announcement said water management practices and improved water conservation led to a consistent decrease in groundwater use along coastal Georgia. Chatham County groundwater use decreased from 85.5 million gallons per day (Mgal/d) in 1990 to 68.2 Mgal/d in 2000, 54.3 Mgal/d in 2010, and 43.2 Mgal/d during 2020.

Glynn County groundwater use decreased from 71.9 million gallons per day (Mgal/d) in 1990 to 53.7 Mgal/d in 2000, 49.0 Mgal/d in 2010, and 39.8 Mgal/d during 2020. The USGS said studies provided new insight into multilayer groundwater-flow systems and improved delineation of saltwater contamination through time in the Upper Floridan aquifer along coastal Georgia.